Finally, we return to the ground vibrations measured in Central Park that we looked at in section Seismic Noise in NYC. However, because we need a waveform that oscillates around zero in order to turn it into sound, we remove the daily running average from the minute-by-minute measurements. The resulting waveform and spectrogram is shown below.
The daily noise cycle due to people and traffic can be heard clearly. The daily signal is also the main feature of the waveform and appears as a bright streak along the bottom of the spectrogram. It and can be heard